Negative Regulation

Abstract

Each of the hypotheses implicitly or explicitly put forward in chapter XIII has been borne out by relevant experiments: enzyme induction is correlated with the synthesis of a specific messenger RNA; the cytoplasmic repressor coded by the i gene has been isolated and characterized; its affinities for the inducer and for the operator have been determined; the repressor extracted from an i ^s strain has lost its affinity for IPTG; the operator is a DNA segment which specifically binds the repressor; finally the inducer displaces the repressor from its complex with the operator. We shall now describe briefly these experiments.